Ink jet recording method

Abstract

An ink jet recording method uses an ink jet recording apparatus including a plurality of heads arranged in parallel in a first direction, each of which ejects droplets of a different radiation-curable ink composition onto a recording medium, and first light sources provided for corresponding heads so as to be disposed at a predetermined side of the corresponding heads. The first light sources emit active radiation to irradiate the droplets on the recording medium. The method includes ejecting droplets of the ink compositions from the heads onto the recording medium, and performing a first irradiation by irradiating the droplets of each ink composition with the active radiation from the corresponding first light source at an irradiation energy within 500 ms after the droplets have landed. The irradiation energy is in the range of 5% to 10% of the energy E 90 at which the ink composition is 90% cured.

The invention claimed is: 
     
       1. An ink jet recording method using an ink jet recording apparatus including a plurality of heads including first and second heads that respectively eject droplets of first and second radiation-curable ink compositions that are different from each other onto a recording medium, a plurality of first light sources that respectively emit an active radiation to irradiate the droplets on the recording medium, the second head being located next to the first head in a first direction, and the first and second heads being located in a carriage, the method comprising:
 transporting the recording medium in a second direction perpendicular to the first direction; 
 ejecting the droplets of the first and second radiation-curable ink compositions from the first and second heads onto the recording medium while the first and second heads are scanning in the first direction; 
 performing an irradiation by irradiating the droplets of the first and second radiation-curable ink compositions with the active radiation from the plurality of first light sources at a first irradiation energy, one of the plurality of first light sources being located next to the first head in the first direction, another of the plurality of first light sources being located next to the second head in the first direction; and 
 performing a further irradiation by irradiating the droplets of the first and second radiation-curable ink compositions irradiated by the plurality of first light sources, the further irradiation being conducted by a second light source at a second irradiation energy, the second light source being located further on a downstream side of the second direction than the plurality of heads and the plurality of first light sources, wherein 
 each of the plurality of first light sources includes an LED, 
 the each of the first and second radiation-curable ink compositions contains a photopolymerization initiator of 5% to 15% by mass, 
 the photopolymerization initiator contains an acylphosphine oxide-based photopolymerization initiator, and 
 a total irradiation energy of the droplets with the active radiation is more than or equal to an energy that is required for curing 90% of the first and second radiation-curable ink compositions. 
 
     
     
       2. The method according to  claim 1 , wherein
 the acylphosphine oxide-based photopolymerization initiator contains bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide. 
 
     
     
       3. The method according to  claim 1 , wherein
 the irradiation is performed by pinning the droplets of the first and second radiation-curable ink compositions and further curing the droplets of the first and second radiation-curable ink compositions. 
 
     
     
       4. The method according to  claim 1 , wherein
 each of the first and second radiation-curable ink compositions is one of a black ink composition, a yellow ink composition, a cyan ink composition, and a magenta ink composition. 
 
     
     
       5. The method according to  claim 1 , wherein
 the further irradiation irradiated by the second light source is performed after the irradiation irradiated by the plurality of first light sources is performed and the recording medium is transported. 
 
     
     
       6. An ink jet recording method using an ink jet recording apparatus including a plurality of heads including first and second heads that respectively eject droplets of first and second radiation-curable ink compositions that are different from each other onto a recording medium, a plurality of first light sources that respectively emit an active radiation to irradiate the droplets on the recording medium, the second head being located next to the first head in a first direction, and the first and second heads being located in a carriage, the method comprising:
 transporting the recording medium in a second direction perpendicular to the first direction; 
 ejecting the droplets of the first and second radiation-curable ink compositions from the first and second heads onto the recording medium while the first and second heads are scanning in the first direction; 
 performing an irradiation by irradiating the droplets of the first and second radiation-curable ink compositions with the active radiation from the plurality of first light sources at a first irradiation energy, one of the plurality of first light sources being located next to the first head in the first direction, another of the plurality of first light sources being located next to the second head in the first direction; and 
 performing a further irradiation by irradiating the droplets of the first and second radiation-curable ink compositions irradiated by the plurality of first light sources, the further irradiation being conducted by a second light source at a second irradiation energy, the second light source being located further on a downstream side of the second direction than the plurality of heads and the plurality of first light sources, wherein 
 each of the plurality of first light sources includes an LED, 
 the each of the first and second radiation-curable ink compositions contains a photopolymerization initiator of 5% to 15% by mass, 
 the photopolymerization initiator contains an acylphosphine oxide-based photopolymerization initiator, and 
 energy, which is required for curing 90% of the first and second radiation-curable ink compositions, is in a range of 120 to 300 mJ/cm 2 . 
 
     
     
       7. The method according to  claim 6 , wherein
 the acylphosphine oxide-based photopolymerization initiator contains bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide. 
 
     
     
       8. The method according to  claim 6 , wherein
 the irradiation is performed by pinning the droplets of the first and second radiation-curable ink compositions and further curing the droplets of the first and second radiation-curable ink compositions. 
 
     
     
       9. The method according to  claim 6 , wherein
 each of the first and second radiation-curable ink compositions is one of a black ink composition, a yellow ink composition, a cyan ink composition, and a magenta ink composition. 
 
     
     
       10. The method according to  claim 6 , wherein
 the further irradiation irradiated by the second light source is performed after the irradiation irradiated by the plurality of first light sources is performed and the recording medium is transported. 
 
     
     
       11. An ink jet recording method using an ink jet recording apparatus including a plurality of heads including first and second heads that respectively eject droplets of first and second radiation-curable ink compositions that are different from each other onto a recording medium, a plurality of first light sources that respectively emit an active radiation to irradiate the droplets on the recording medium, the second head being located next to the first head in a first direction, and the first and second heads being located in a carriage, the method comprising:
 transporting the recording medium in a second direction perpendicular to the first direction; 
 ejecting the droplets of the first and second radiation-curable ink compositions from the first and second heads onto the recording medium while the first and second heads are scanning in the first direction; 
 performing an irradiation by irradiating the droplets of the first and second radiation-curable ink compositions with the active radiation from the plurality of first light sources at a first irradiation energy, one of the plurality of first light sources being located next to the first head in the first direction, another of the plurality of first light sources being located next to the second head in the first direction; and 
 performing a further irradiation by irradiating the droplets of the first and second radiation-curable ink compositions irradiated by the plurality of first light sources, the further irradiation being conducted by a second light source at a second irradiation energy, the second light source being located further on a downstream side of the second direction than the plurality of heads and the plurality of first light sources, wherein 
 each of the plurality of first light sources includes an LED, 
 the each of the first and second radiation-curable ink compositions contains a photopolymerization initiator of 5% to 15% by mass, 
 the photopolymerization initiator contains an acylphosphine oxide-based the photopolymerization initiator, and 
 a total irradiation energy of the first and second irradiation energies is greater than or equal to E90(mJ/cm2) at which the first and second radiation-curable ink compositions are 90% cured. 
 
     
     
       12. The method according to  claim 11 , wherein
 the acylphosphine oxide-based photopolymerization initiator contains bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide. 
 
     
     
       13. The method according to  claim 11 , wherein
 the irradiation is performed by pinning the droplets of the first and second radiation-curable ink compositions and further curing the droplets of the first and second radiation-curable ink compositions. 
 
     
     
       14. The method according to  claim 11 , wherein
 each of the first and second radiation-curable ink compositions is one of a black ink composition, a yellow ink composition, a cyan ink composition, and a magenta ink composition. 
 
     
     
       15. The method according to  claim 11 , wherein
 the further irradiation irradiated by the second light source is performed after the irradiation irradiated by the plurality of first light sources is performed and the recording medium is transported. 
 
     
     
       16. An ink jet recording method using an ink jet recording apparatus including a plurality of heads including first and second heads that respectively elect droplets of first and second radiation-curable ink compositions that are different from each other onto a recording medium, a plurality of first light sources that respectively emit an active radiation to irradiate the droplets on the recording medium, the second head being located next to the first head in a first direction, and the first and second heads being located in a carriage, the method comprising:
 transporting the recording medium in a second direction perpendicular to the first direction; 
 ejecting the droplets of the first and second radiation-curable ink compositions from the first and second heads onto the recording medium while the first and second heads are scanning in the first direction; 
 performing an irradiation by irradiating the droplets of the first and second radiation-curable ink compositions with the active radiation from the plurality of first light sources at a first irradiation energy, one of the plurality of first light sources being located next to the first head in the first direction, another of the plurality of first light sources being located next to the second head in the first direction; and 
 performing a further irradiation by irradiating the droplets of the first and second radiation-curable ink compositions irradiated by the plurality of first light sources, the further irradiation being conducted by a second light source at a second irradiation energy, the second light source being located further on a downstream side of the second direction than the plurality of heads and the plurality of first light sources, wherein 
 each of the plurality of first light sources includes an LED, 
 the each of the first and second radiation-curable ink compositions contains a photopolymerization initiator of 5% to 15% by mass, 
 the photopolymerization initiator contains an acylphosphine oxide-based photopolymerization initiator, and 
 the further irradiation is performed after 500 ms has elapsed from the landing of the droplets of first and second radiation-curable ink compositions to the recording medium. 
 
     
     
       17. The method according to  claim 16 , wherein
 the acylphosphine oxide-based photopolymerization initiator contains bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide. 
 
     
     
       18. The method according to  claim 16 , wherein
 the irradiation is performed by pinning the droplets of the first and second radiation-curable ink compositions and further curing the droplets of the first and second radiation-curable ink compositions. 
 
     
     
       19. The method according to  claim 16 , wherein
 each of the first and second radiation-curable ink compositions is one of a black ink composition, a yellow ink composition, a cyan ink composition, and a magenta ink composition. 
 
     
     
       20. The method according to  claim 16 , wherein
 the further irradiation irradiated by the second light source is performed after the irradiation irradiated by the plurality of first light sources is performed and the recording medium is transported.